Dual purpose shipping and display cartons having removable sections or panels defined by perforated tear lines are known. Such cartons are typically formed from a one-piece blank which has been suitably cut and scored to enable subsequent folding of the blank into a closed carton. The removable section(s) is generally defined by a plurality of perforated lines and may be separated from the closed carton by tearing out such section along the perforated lines.
The inclusion of perforation lines reduces the structural integrity of the cartons. Difficulty has been encountered in preventing inadvertent opening of the lines during storage or shipment. Unwanted opening of these lines exposes and subjects the articles contained therein to loss or theft, resulting in delayed or unfilled orders, spillage, and ultimately increased expense to consumers.
Inadvertent opening of the carton along the perforation lines depends largely on the stresses to which the filled cartons are subjected during handling and shipping. Stressful treatment of the cartons is to some extent uncontrollable, e.g., tall heavy stacks of the filled cartons are commonly needed or used for maximum efficient utilization of warehouse or cargo space, which develops high stress on the lower layers of the stacks. Also, inadvertent opening is especially likely during storage or shipment of relatively heavy articles.
The problem of inadvertent opening of perforation lines is compounded by the desire to employ as little carton material, i.e., carton weight, as possible, in the interest of materials cost savings. A reduction of the carton weight is accompanied by a diminution in carton strength and capability of containing articles without tearing, especially for articles of substantial weight. Thus, while cartons of lesser weight, i.e., less material, thinner panels and flaps, etc., are desirable from an economic point of view, as well as for ease of removing the removable sections, so are structurally strong and stable cartons which reliably contain the contents therein during shipping and handling. These objectives are at cross purposes and no combination shipping and display carton is known which optimally balances these competing objectives, especially for dense or heavy loads such a bar soaps.
The ratio of the weight of the contents of the carton to the weight of the carton may be viewed as a measure of packaging efficiency. Thus, higher ratios correspond to more efficient packaging. However, there are practical limits beyond which the carton strength is so low relative to the load that a reliable package is not feasible. Furthermore, this ratio is generally less for cartons having removable sections due to the inclusion of perforation lines, compared to the generally stronger cartons that can be fabricated without removable sections.
The difficulty of known dual purpose cartons in reliably containing high loads, especially articles of substantial density or weight such as bar soap, in a carton of minimum weight, is compounded by the desire for large removable sections. Large removable sections are desired to permit a substantial and attractive display of the articles and to facilitate removal of unit amounts thereof from retail shelves or counters by purchasers. However, large removable sections weaken correspondingly large portions of the relatively light weight carton.